KR20120023725A - Method for storing lanthanum oxide target, and vacuum-packed lanthanum oxide target - Google Patents

Abstract

A storage method of a sputtering target made of lanthanum oxide, wherein a film of lanthanum fluoride to be stored is formed in a vacuum pack having an oxygen transmission rate of 0.1 cm 3 / m 2 -24 h -atm or less and a water vapor transmission rate of 0.1 g / m 2 -24 h or less. A lanthanum oxide target storage method comprising charging a lanthanum oxide target and lanthanum oxide powder, charging the target and the powder, and then vacuum-sucking and encapsulating the vacuum pack. Studying the storage method of the target which consists of an oxide of lanthanum which is a rare earth metal, and suppresses the powdering phenomenon by the hydration reaction (hydration) of the target by the residual and invasion of air, and also the powdering phenomenon by the formation of carbonate, Provided is a technique that enables long-term storage in a state where it can be used as a sputtering target.

Description

METHOD FOR STORING LANTHANUM OXIDE TARGET, AND VACUUM-PACKED LANTHANUM OXIDE TARGET}

The present invention relates to a method for storing a lanthanum oxide target that is easily pulverized by hydroxylation and a vacuum sealed lanthanum oxide target.

Lanthanum, a rare earth metal, is contained in the earth's crust as a mixed complex oxide. Rare earth metals are given this name because they are separated from relatively rare minerals, but they are by no means rare throughout the earth's crust. In recent years, the rare earth metal is attracting attention as an electronic material, and research and development is progressing.

Among these rare earth metals, lanthanum (La) is particularly noticed. Briefly introducing this lanthanum, the lanthanum has an atomic number of 57 and a white metal having an atomic weight of 138.9, and has a close hexagonal structure at room temperature. Melting | fusing point is 921 degreeC, boiling point 3500 degreeC, and density 6.15 g / cm <3>, The surface is oxidized in air, and it melt | dissolves in water gradually.

It is soluble in hydrothermal and acid. There is no ductility, but there is some malleability. The resistivity is 5.70 × 10 ⁻⁶ Ωcm. Is burned in the over 445 ℃ becomes oxide (La ₂ O ₃₎ (see Physicochemical Dictionary). In general, rare earth metals have a stable compound of oxidized water 3, but are lanthanum trivalent.

This lanthanum is a metal attracting attention as an electronic material, such as a metal gate material and a high dielectric constant material (High-k). Rare earth metals other than lanthanum also have similar properties to lanthanum.

Rare earth metals such as lanthanum are materials that are difficult to be highly purified because of the problem of being easily oxidized during purification. Moreover, when rare earth metals, such as lanthanum, are left to air, since it oxidizes and discolors in a short time, there exists a problem that handling is not easy.

In recent years, a thin film is required as a gate insulating film in a next-generation MOSFET. However, in SiO _{2 which} has been used as a gate insulating film so far, the leakage current due to the tunnel effect increases, making it difficult to operate normally.

For this reason, HfO ₂ , ZrO ₂ , Al ₂ O ₃ , La ₂ O ₃ , which have high dielectric constant, high thermal stability, and high energy barrier to holes and electrons in silicon, have been proposed as a substitute. In particular, among these materials, evaluation of La ₂ O ₃ is high, and electrical characteristics are investigated, and research reports as a gate insulating film in next-generation MOSFETs have been made (see Non-Patent Document 1). However, in the case of this patent document, it is La ₂ O ₃ film | membrane which has been studied, and the hygroscopicity of the lanthanum oxide target and the behavior of powdering phenomenon are not specifically mentioned.

As such, rare earth metals such as lanthanum and oxides thereof are still in the research stage. However, when investigating such rare earth metals and their oxide characteristics, rare earth metal oxides, particularly lanthanum oxides themselves, exist as sputtering target materials. In this case, a thin film of lanthanum oxide can be formed directly on the substrate, and the behavior of the interface with the silicon substrate, and moreover, the rare earth metal compound can be formed to investigate the properties of the high dielectric constant gate insulating film and the like. It has a big advantage that the degree of freedom as.

However, even if a lanthanum sputtering target is produced, it oxidizes in a short time in air as mentioned above. In general, a stable oxide film is formed on the surface of the metal target, but since it is usually very thin, it is not peeled off at the beginning of sputtering so that it does not greatly affect the sputtering characteristics. However, in the lanthanum sputtering target, an oxide film becomes thick, electrical conductivity falls, and it causes a sputtering defect.

In addition, when left in the air for a long time, it reacts with moisture in the air, is covered with a white powder of hydroxide, and finally comes into a powdered state, and even a problem that normal sputtering is impossible is generated. For this reason, it is necessary to take a vacuum pack or cover it with fats and oils immediately after preparation of a target, and take the measures to prevent oxidation and a hydration reaction.

As a storage method of the rare earth metal, storage in mineral oil is common in order to avoid contact with the atmosphere. However, when used as a sputtering target, it is necessary to clean the mineral oil before use to remove it. However, there is a problem that cleaning itself is difficult due to the reactivity with oxygen, moisture, and carbon dioxide as described above.

Therefore, it is usually necessary to store and pack with a vacuum pack. By the way, since the powdering by hydroxide advances even with the slight moisture which permeate | transmits the film used even in the state used as a vacuum pack, long-term storage in the state which can be used as a sputtering target was difficult.

According to the known art, a method of covering a cathode sputtering target with a resin bag alone (see Patent Document 1), a method of attaching a protective film of a plastic film to the target (see Patent Document 2), and no detachable particles exist A method of packing a target using a film on the surface (see Patent Document 3), a method of preparing a storage container of the target using a top cover of a transparent acrylic resin, screw fixing (see Patent Document 4), and a sputtering target bag There is a method (see patent document 5) to enclose in a shaped object. However, these encapsulate a target using the lid | cover of resin or resinous film, and it is not enough as the storage method of the target which consists of a lanthanum oxide.

Moreover, it is reported that the powder of a lanthanum oxide is put into the hydrofluoric acid aqueous solution, the film of lanthanum fluoride is formed in the surface of a powder, and it is effective in suppressing a hydration reaction (refer patent document 6). This is for reference, but since the object is a powder of lanthanum oxide, it is unclear whether it is suitable for the target (bulk shape, block shape).

In this regard, the present applicant is a method for storing a sputtering target made of lanthanum oxide, and includes lanthanum in a vacuum pack having an oxygen transmission rate of 0.1 cm 3 / m 2 -24 h -atm or less and a water vapor transmission rate of 0.1 g / m 2 -24 h or less. After charging an oxide target and lanthanum oxide powder, loading the target and powder, the vacuum pack was vacuum-aspirated and sealed, and the storage method of the lanthanum oxide target was developed (refer patent document 7).

This storage method is very effective and has the effect of suppressing the powdering phenomenon by the hydration reaction (hydration) which is remarkably superior compared with the past, and also the powdering phenomenon by the formation of carbonate. However, there is a need to further improve this storage method.

International Publication WO2005 / 037649 Japanese Laid-Open Patent Publication 2002-212718 Japanese Laid-Open Patent Publication 2001-240959 Japanese Patent Laid-Open No. 8-246135 Japanese Patent Laid-Open No. 4-231461 Japanese Unexamined Patent Publication No. 10-87326 International Publication WO2010 / 050409

 Esuke Tokumitsu, et al., Published "A Study of Oxide Materials for High-k Gate Insulators", The Institute of Electrical and Electronics Engineers, Vol.6-13, Page.37-41, September 21, 2001

The present invention studies a method of storing a target made of an oxide of lanthanum, which is a rare earth metal. It is an object of the present invention to provide a technology that enables a long-term storage in a state of being suppressed and usable as a sputtering target.

The present invention,

1) As a method for storing a sputtering target made of lanthanum oxide, a film of lanthanum fluoride is formed on the target surface of lanthanum oxide to be stored in advance, and then the oxygen transmittance is 0.1 cm 3 / m 2 -24 h? Atm or less, and the water vapor transmittance is A method of storing a lanthanum oxide target is provided in which a lanthanum oxide target having a film of lanthanum fluoride formed therein is charged in a vacuum pack of 0.1 g / m 2 -24 h or less, followed by vacuum suction and sealing. do.

A major feature of the present invention is to form a film of lanthanum fluoride on the target surface of the lanthanum oxide to be stored in advance, whereby the powdering phenomenon by the hydration reaction (hydration) of the target, and further the powdering by the formation of carbonate The suppression of the phenomenon can be significantly increased. Moreover, the more preferable conditions of a vacuum pack have the property that oxygen transmittance is 0.08 cm <3> / m <2> -24 h * atm or less, and water vapor transmittance is 0.02 g / m <2> -24 h or less. The same applies to the vacuum pack described below.

The present invention,

2) As a method for storing a sputtering target made of lanthanum oxide, a film of lanthanum fluoride is formed on the target surface of lanthanum oxide to be stored in advance, and then the oxygen transmittance is 0.1 cm 3 / m 2 -24 h? Atm or less and the water vapor transmittance is After charging the lanthanum oxide target and the lanthanum oxide powder which formed the said lanthanum fluoride film in the vacuum pack of 0.1 g / m <2> -24h or less, the vacuum pack is vacuum-sucked and sealed, and is stored Provide storage methods.

The present invention,

3) The method for storing the lanthanum oxide target according to 1) or 2) above, wherein the lanthanum oxide target has a purity of 3 N or more and a gas component of C is 100 wtppm or less.

The present invention,

4) A sputtering target made of lanthanum oxide sealed in a vacuum pack for storage, wherein a film of lanthanum fluoride is formed on the target surface of the lanthanum oxide to be stored in advance, and the oxygen transmittance of the vacuum pack is 0.1 cm 3 / m 2 -24 h lanthanum oxide sealed in a vacuum pack having? atm or less, water vapor transmission rate of 0.1 g / m 2 -24h or less, and a lanthanum oxide target having a film of said lanthanum fluoride charged and sealed in the vacuum pack. It provides a sputtering target consisting of.

The present invention,

5) A sputtering target made of lanthanum oxide sealed in a vacuum pack for storage, wherein a film of lanthanum fluoride is formed on the target surface of the lanthanum oxide to be stored in advance, and the oxygen transmittance of the vacuum pack is 0.1 cm 3 / m 2 -24 h atm or less, the water vapor transmission rate is 0.1 g / m 2 to 24 h or less, and in the vacuum pack, a lanthanum oxide target and a lanthanum oxide powder having a film of the lanthanum fluoride are charged and encapsulated. Provided is a sputtering target made of sealed lanthanum oxide.

The present invention,

6) The sputtering target which consists of lanthanum oxide sealed in the vacuum pack as described in said 4) or 5) characterized by the purity of a lanthanum oxide target being 3N or more and content of C which is a gas component is 100 wtppm or less.

The present invention,

7) Said 4) which is characterized in that the relative density of the sputtering target which consists of lanthanum oxide is 96% or more. The sputtering target which consists of lanthanum oxide sealed in the vacuum pack as described in any one of 6) is provided.

The present invention,

8) above 4)? The sputtering target which consists of lanthanum oxide sealed in the vacuum pack of any one of 7) is released by the vacuum release after storage, and the thin film formed by sputtering using the target which consists of lanthanum oxide taken out is provided.

In the case of storing the conventional rare earth metal or the target made of these oxides in an airtight container or a plastic film, if left for a long time, the state covered with white powder of hydrate (hydroxide) reacts with oxygen and moisture. The sputtering target which consists of a lanthanum oxide which forms the film of lanthanum fluoride on the target surface of the lanthanum oxide which should be preserve | saved beforehand, seals in a vacuum pack, and stored it for a long time, although a problem arises that a normal sputtering becomes impossible. The preservation of is possible and does not cause such a problem.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure (photograph) which shows the unopened target after 4 months and the target state when it cleans when the La oxide target is vacuum-packed.
2 shows two days immediately after removing the La oxide target from the vacuum pack and in air. It is a photograph of the appearance when left for 15 days.
3 is an external photograph after two weeks of storage when a vacuum pack (GX barrier) is used.
4 shows XRD measurement results of each La ₂ O ₃ target immediately after hot pressing, after two weeks of storage in a vacuum pack, and after two weeks of storage in the air.
FIG. 5 is a diagram illustrating a test by vacuum-packing a silica gel used as a dehumidifying agent with a target.
6 is a view showing the results of the case of using La ₂ O ₃ powder as desiccant.
7 is an X-ray diffraction image (XRD) of a target when vacuum-packed using La ₂ O ₃ powder.
8 is a view showing test results for confirming the pulverization phenomenon of La ₂ O ₃ target when the paraffin coating.
FIG. 9 is a view showing test results for confirming powdering phenomenon of a La ₂ O ₃ target when Teflon (registered trademark, hereafter identical) is coated. FIG.
10 is a view showing the test results for confirming the phenomenon powder of La ₂ O ₃ target in the case of fluoride coating film.
11 is a diagram showing the trend of the powder results phenomenon in the case of combined fluoride film coating and vacuum packs for La ₂ O ₃ target.
12 is a view showing an analysis result by the X-ray diffraction of the La ₂ O ₃ target in the case of combined fluoride film coating and vacuum packs.
13 is a diagram showing the trend of the powder results in the phenomenon of La ₂ O ₃ target case of combined fluoride film coating, vacuum packs, and dehumidifying the re-La ₂ O ₃ powder.
14 is a view showing an analysis result by the X-ray diffraction of the fluoride film coating, vacuum packs, and dehumidifying the re-La ₂ O La ₂ O ₃ target in the case of combined _three powders.

Lanthanum oxide is known to be extremely hygroscopic (reactive with moisture, hydration reaction). Therefore, until now, how to prevent lanthanum oxide from being absorbed or stored in an environment with low moisture has been a problem.

Below, description of the powdering phenomenon of the conventional lanthanum oxide target and the means to solve this, including a specific example of an Example and a comparative example, are demonstrated using a chart etc.

Recently, work function adjusting layer of high-k ash for PMOS (La ₂ O ₃ ) The demand for La system targets is increasing. When La is stored in the atmosphere, it first rapidly changes to La ₂ O ₃ and there, to La (OH) ₃ , and collapses into a powder form.

For example, when the La ₂ O ₃ target was vacuum-packed and shipped to the demand destination, all of the powders were ejected from the shipment to the opening, and a problem occurred such as a bundle of particles and the target outer peripheral portion collapsed. The state is shown in FIG. The upper figure is a photograph which shows the surface state of the unopened target four months after shipment. Moreover, the lower figure is a photograph which shows the surface state which surface-cleaned the target after 4 months of shipment.

As is evident from this photograph, the powdering phenomenon in particular occurs at the edge of the target. Cleaning the surface restores the surface condition to some extent except for the edges, but causes the problem of always cleaning the surface when using the target.

In order to solve the above problem, it is necessary to observe how the hydration reaction is progressing and to prevent it.

In general, to prepare a La ₂ O ₃ target, La ₂ O ₃ powder is prepared by hot pressing under vacuum at a temperature of about 1300 ℃. In this case, it is the purity of the La ₂ O ₃ powder is preferably higher in order to improve the purity of the target. The purity of the target requires 3 N levels. As described above, not only moisture in the air but also carbon dioxide forms carbonates and is related to the powdering phenomenon. Therefore, the presence of carbon (C) in the target needs special attention. In addition, the density of the target also affects the powdering phenomenon. This is because the presence of voids affects hygroscopicity.

Under vacuum, it was investigated at what rate the hydration reaction of the La ₂ O ₃ target obtained by hot pressing progressed. 2, two days in the air? The external photograph when leaving for 15 days is shown. In addition, the test was carried out in June in an environment of dry operation at room temperature 23 ° C. with an air conditioner.

The next day, La (OH) ₃ powder began to spout on the surface, and was completely buried on the 3rd day. After two weeks all became powder. From the above results, it was found that the powdering phenomenon proceeds violently in the atmosphere, and therefore it is necessary to completely block the target from the atmosphere. Therefore, the storage test in the vacuum pack (GX barrier) was implemented.

FIG. 3 is a photograph of appearance after two weeks of storage when a La ₂ O ₃ target is vacuum packed (GX barrier). FIG. You can't see the direct powder, but you can see it gradually changes from gray to white. About the above, each XRD measurement result is shown in FIG.

The top of Figure 4 resulting XRD measurement of the La ₂ O ₃ target immediately after the hot press, stop the XRD measurement of the two weeks, La ₂ O ₃ target and after storage in a vacuum pack result, the bottom is La ₂ O ₃ after two weeks in the atmosphere kept The XRD measurement result of a target is shown.

Immediately after the hot press, the La ₂ O ₃ single phase slowly began to hydrate, and after two weeks, the peak intensity ratio of La ₂ O ₃ to La (OH) ₃ (La ₂ O ₃ The maximum intensity ratio of La (OH) ₃ to (101 in La ₂ O ₃ and (110) in La (OH) ₃ ) is about 50:50, and half of the surface layer in the vacuum pack is La (OH) _3. In the atmosphere, all finally changed to La (OH) ₃ . Hydration can be delayed in the vacuum pack, but it can be seen that it is impossible to prevent. In the case of vacuum sealing and storage, it is preferable to vacuum seal the container or the film-shaped seal once after replacing it with an inert gas having a dew point of -80 ° C or lower. As a means of sealing storage, a flexible film can be used and it can be vacuum-sealed as a sealed bag.

(Use of dehumidifier)

In view of the above results, it was found that the storage in the vacuum pack alone was insufficient. Therefore, it is considered that the moisture permeated into the vacuum pack should be removed, and the use of the dehumidifying agent was considered. First, silica gel, which is generally used as a dehumidifying agent, was packaged and tested with the target. In FIG. 5, the external photograph on the 1st day and 15th day of storage is shown.

The packing of silica gel together produced more La (OH) ₃ than in the case of only the flexible film. This is considered to be because the granules are large in silica gel, many gaps remain after the vacuum pack, and a large amount of moisture that has not been completely exhausted remains.

(Use of La ₂ O ₃ powder)

Therefore, La ₂ O ₃ powder was used as a material having no gap even after the pack and a strong absorbing power. Since La ₂ O ₃ powder itself contains a lot of water, the La ₂ O ₃ powder was subjected to degassing treatment at 1000 ° C. × 1.5 h in a vacuum furnace. The photograph of the result is shown in FIG. 6 below. Top left is the first day when the storage (before the vacuum pack), the top right is a vacuum pack by using La ₂ O ₃ powder, and the lower is a view showing the storage result of the storage 1 month.

Even after 1 month, no discoloration of the surface was observed, and the X-ray diffraction image (XRD) of this target is shown in FIG. 7. Even when the XRD of FIG. 7 is observed, the peak intensity ratio of La ₂ O ₃ and La (OH) ₃ is observed. (La ₂ O ₃ and La (OH) peak intensity ratio (110) of La ₂ O ₃ (101) and La (OH) ₃ of ₃ is about a 90: 10, compared to the flexible film when ten thousand and one The hydrate was greatly reduced.

This result is considered to be because the gap is not generated by using the powder and a material having high hygroscopicity is used. Compared with the flexible film alone, the shelf life is dramatically improved.

In addition, even when lanthanum oxide reacts with water to be hydrated, powdered, and adhered to the target surface, since the lanthanum oxide is a compound of the same metal and is powder, it is not a cause of contamination since it is easy to remove. This is also a significant advantage compared with the case of using the drying agent which consists of other metals.

In this way, the outside air is blocked and moisture intrusion of the outside air is suppressed as much as possible, but even if there is a slight invasion, the lanthanum oxide used as a desiccant is placed or filled in the space generated when encapsulating the hydroxide of the target body. It becomes possible to suppress it.

Generally, a target is bonded to a backing plate, but when this is used, for example using a flexible film and vacuum-sealed as an airtight bag, an unavoidable step | step arises between a target and a backing plate, and an air gap is easy to generate | occur | produce. . Outside air easily accumulates in such a gap. And the powder shape of a target will advance easily from there. It is preferable to fill the lanthanum oxide which becomes a desiccant into such a level | step difference or a space | gap.

The lanthanum oxide powder which becomes this desiccant will understand that powder or granule state with a large surface area is good in this sense. However, it is effective only to place a small lump of lanthanum oxide in a place where outdoor air is easy to store.

In addition, it is most effective to leave the lanthanum oxide in direct contact with the target, but the adhesion of powder to the surface of the target may cause particle generation during sputtering. In such a case, even if it encloses in the state packed into the moisture-permeable film like a general desiccant, it is effective.

In the storage method of the target of the present invention, the above-described lanthanum oxide powder used as a drying agent is a contradictory expression, but as the storage method of the target consisting of lanthanum oxide, the lanthanum oxide which is most easily hydroxylated is a rare earth metal or a target composed of the oxide thereof. It is the highest inhibitory effect on hydroxide.

The moisture permeation amount of the flexible film used for bag storage or the moisture penetration amount from the outside of the container is set to 0.1 g / m 2 to 24 h or less to prevent the intrusion of moisture as much as possible. It is important.

As a preferable example of the flexible film used for the vacuum pack whose oxygen transmittance is 0.1 cm <3> / m <2> -24 h * atm or less, and the water vapor transmittance | permeability is 0.1 g / m <2> -24 h or less, it is effective to have a characteristic more than a GX barrier (brand name). . GX barrier (brand name) and Al foil containing bag are preferable. This represents a representative example, and it goes without saying that other flexible films can be used as long as the above conditions are satisfied. As for the above, this applicant has shown in the said patent document 7.

(Surface coating)

Although the said method is effective, it is easy to blow off powder because there is much time exposed to air | atmosphere during target preparation. As a countermeasure, surface coating was attempted.

First, a test was performed with a coating material (paraffin and Teflon coat) containing no water nearby.

Moreover, hydrofluoric acid treatment test was also performed because there exists patent document 6 which shows that water resistance increases when a fluoride film is coated on the surface by the treatment with hydrofluoric acid. In this case, it is to be immersed in hydrofluoric acid for 24 hours, to form a stable LaF ₃ film in the air on the surface to stabilize in the air. These results are shown below.

8 is a paraffin coating test result, FIG. 9 is a Teflon coating test result, and FIG. 10 is a fluorine coating test result.

All coatings lasted 1 day, but after 2 days flour was generated. They all occurred at the rough surface or at the edge where the film is hard to attach.

As the paraffin was generated at La (OH) ₃ at one point, powder was generated on the entire surface. This is thought to be because volume expansion occurs during hydration, and the film cannot withstand it. In Teflon spray, wettability was bad, and the powder ejection method was the largest. In the above, it was thought that only paraffin and Teflon spray did not reach a fundamental solution. The same was true for hydrofluoric acid treatment (formation of fluoride film).

This was contrary to the fact described in patent document 6. However, while Patent Document 6 was carried out on a La ₂ O ₃ powder, in the present invention, since it was carried out on a bulky La ₂ O ₃ target, the properties of the object were different and it was unreasonable to expect the same effect.

As described above, the hydrofluoric acid treatment was also considered to produce the same phenomenon as paraffin, but no powder was observed at all depending on the place (particularly the side surface). Moreover, in the said surface coating method, it turned out that it is 1 day at most, even if the storage period in air | atmosphere is extended.

However, by using a hydrofluoric acid treatment and a vacuum pack together, the idea that the storage period can be expected to be further improved was reached. Then, after hydrofluoric acid treatment, it was stored in a vacuum pack for irradiation.

(Combination of Fluoride Coating and Vacuum Pack)

As a result of the pulverization phenomenon when the fluoride film coating and the vacuum pack for this La ₂ O ₃ target are used in combination, that is, the pulverization transition photograph of the La ₂ O ₃ target is shown in FIG. 11.

In addition, it is shown in the case of La ₂ O ₃ 12 to X-ray diffraction test results of the target.

In this way, the hydration did not proceed much after one month by attaching the fluorinated film and storing in a vacuum while increasing the moisture resistance. La ₂ O ₃ and La (OH) ₃ up to a peak intensity ratio (La ₂ O ₃ (101) and La (OH) ₃ (110)) of 90: 10 was about (In the vacuum pack 10 045: 55 or so).

(Combination of fluorinated film coating, vacuum pack and La ₂ O ₃ powder as dehumidifier)

Based on the test results, irradiation was carried out to store the surface coating with hydrofluoric acid and the dehumidifying material of La ₂ O ₃ , which were effective for extending the storage period, in a vacuum pack.

The change of the powdering phenomenon of a target of this result is shown in FIG. Also, it is shown in the case of La ₂ O ₃ 14 also the X-ray diffraction test results of the target.

As shown in FIG. 13, fluoride coating film had an effect, La ₂ O ₃ powder, by a combination of vacuum pack, even after one months La ₂ O ₃ target was not changed little. In addition, as shown in Fig. 14, La ₂ O ₃ and La (OH) ₃ peak intensity ratio of (the La ₂ O ₃ (101) and La (OH) ₃ of 110) is 98: in 2 degree.

The La ₂ O ₃ sintered compact target reacted with moisture in the air and was easily changed to La (OH) ₃ . Although the storage period could be extended by blocking the outside air by the vacuum pack, dehumidification in the pack, and surface coating, the hydration could not be completely prevented. However, by using these in combination, almost no change was observed even after one month of storage, and a remarkable improvement effect was confirmed.

Industrial availability

Conventionally, when a rare earth metal oxide, especially a lanthanum oxide sputtering target, is left in the air for a long time, it is in a state of being covered with a white powder of hydroxide due to reaction with moisture in the air, thereby causing a problem that normal sputtering is impossible. The storage method of the target which consists of a lanthanum oxide does not produce such a problem.

The storage method of the target which consists of a lanthanum oxide of this invention basically loads the lanthanum oxide target and lanthanum oxide powder which formed the film of the lanthanum fluoride which should be stored, and after charging the target and powder, Vacuum suction and encapsulation. Thereby, the state which reacts with the moisture in air and is covered with the white powder of hydroxide can be suppressed effectively.

This enables stable supply of the target as an electronic material such as a metal gate material and a high dielectric constant material (High-k), which is very useful industrially.

Claims (8)

As a method for storing a sputtering target made of lanthanum oxide, a film of lanthanum fluoride is formed on the target surface of lanthanum oxide to be stored in advance, and then the oxygen transmittance is 0.1 cm 3 / m 2 -24 h? Atm or less, and the water vapor transmittance is 0.1 g. A lanthanum oxide target storage method characterized by charging a lanthanum oxide target having a film of lanthanum fluoride formed therein into a vacuum pack of 24 m 2/24 h or less, followed by vacuum suction and sealing. As a method for storing a sputtering target made of lanthanum oxide, a film of lanthanum fluoride is formed on the target surface of lanthanum oxide to be stored in advance, and then the oxygen transmittance is 0.1 cm 3 / m 2 -24 h? Atm or less, and the water vapor transmittance is 0.1 g. A lanthanum oxide target storage method, characterized in that the lanthanum oxide target and the lanthanum oxide powder having the lanthanum fluoride coating formed therein are charged in a vacuum pack of 24 m 2/24 h or less, and the vacuum pack is vacuum sucked and sealed. . The method according to claim 1 or 2,
The purity of a lanthanum oxide target is 3 N or more, and the content of C which is a gas component is 100 wtppm or less, The storage method of a lanthanum oxide target. A sputtering target made of lanthanum oxide sealed in a vacuum pack for storage, wherein a film of lanthanum fluoride is formed on the target surface of the lanthanum oxide to be stored in advance, and the oxygen transmittance of the vacuum pack is 0.1 cm 3 / m 2 -24 h · atm The water vapor transmission rate is 0.1 g / m 2 to 24 h or less, and the lanthanum oxide sealed in the vacuum pack is characterized in that a lanthanum oxide target having a film of lanthanum fluoride is charged and enclosed in the vacuum pack. Sputtering Target. A sputtering target made of lanthanum oxide sealed in a vacuum pack for storage, wherein a film of lanthanum fluoride is formed on the target surface of the lanthanum oxide to be stored in advance, and the oxygen transmittance of the vacuum pack is 0.1 cm 3 / m 2 -24 h · atm Hereinafter, the water vapor transmission rate is 0.1 g / m 2 -24 h or less, and in the vacuum pack, a lanthanum oxide target and a lanthanum oxide powder having a film of the lanthanum fluoride are charged and encapsulated in a vacuum pack. Sputtering target consisting of lanthanum oxide. The method according to claim 4 or 5,
A sputtering target made of lanthanum oxide sealed in a vacuum pack, wherein the lanthanum oxide target has a purity of 3 N or more and a gas component of C is 100 wtppm or less. The method according to any one of claims 4 to 6,
A sputtering target made of lanthanum oxide sealed in a vacuum pack, wherein the sputtering target made of lanthanum oxide has a relative density of 96% or more. The thin film which formed the sputtering target which consists of lanthanum oxide sealed in the vacuum pack of any one of Claims 4-7 by sputtering using the target which consists of lanthanum oxide taken out after vacuum release.

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